1. Field of the Invention
The present invention relates to technology related to polishing of substrates, which are objects to be processed, requiring a high flatness processing precision such as for silicon wafers or semiconductor substrates, glass substrates or the like, and particularly relates to technology for which it is possible to realize reuse of polishing pads used when polishing the surface of these substrates.
2. Description of the Related Art
As is well known, when manufacturing semiconductors, a polishing process that flattens the surface of a substrate such as a silicon wafer, semiconductor substrate, glass substrate or the like, which are structural components, is performed. This polishing process is typically implemented by directly fixing a disk shaped polishing pad consisting of resin material or the like using double sided tape on a rotating surface plate of a polishing device, and while supplying polishing liquid containing abrasive grains, doing rotary motion of the polishing pad and the substrate relative to each other to perform polishing.
Then, as a polishing pad for implementing this kind of polishing process, as is noted in Published Unexamined Patent Application No. JP-A-2002-11630 and the like, a resin pad consisting of foaming or non-foaming urethane or the like is used. Also, in many cases, on the polishing surface of this polishing pad, a grooving process is implemented such as in concentric circle form, grid form, radial form or the like, or bubbles of the foaming resin are opened or the like.
In the polishing processing using a polishing pad, the polishing pad sometimes has to be torn off the rotating surface plate and changed to a different polishing pad, upon switching the kind of substrate which is the object to be polished or the like. Also, even in cases such as when reprocessing by surface grooving or the like using a different processing device for the purpose of reuse or the like of polishing pads which have degraded along with the polishing process, for example, it is necessary to tear off the polishing pad from the rotating surface plate.
However, thin disk shaped polishing pads are adhered strongly by adhesive tape to the rotating surface plate of the polishing device, so when tearing off this polishing pad from the rotating surface plate, damage such a bending or warping, wrinkles, breakage or the like occurs easily to the polishing pad. Accordingly, due to this kind of damage, there is the problem that this polishing pad, despite the fact that its product life has not ended, often must be discarded because it cannot be reused.
There is also the problem that the work of tearing off the polishing pad from the rotating surface plate while paying close attention not to cause damage is a great burden on the worker as it requires skill and caution. In addition, there was also the problem that because considerable time is required for the work of tearing the polishing pad off the rotating surface plate, the expensive and valuable polishing device has to be stopped for a long time, limiting the operating time of the device.
In light of this, with Published Unexamined Patent Application No. JP-A-2010-214579, the inventors previously proposed a polishing pad with auxiliary plate made so that an auxiliary plate is attached to the back surface of the polishing pad, and via this auxiliary plate, the polishing pad is adhered by double sided tape to the rotating surface plate of a polishing device. With this polishing pad with auxiliary plate, since the polishing pad is attached and detached in relation to the rotating surface plate while maintaining the state of the polishing pad being supported as is by the auxiliary plate, the auxiliary plate reinforces against damage of the polishing pad when attaching and detaching. This makes it possible to attach and detach the polishing pad in relation to the rotating surface plate with good workability while preventing damage to the polishing pad.
However, after a great deal of further research and study by the inventors, with the polishing pad with auxiliary plate proposed with JP-A-2010-214579, they found it hard to say that it is always easy to be compatible with all polishing devices.
Specifically, when overlapping the polishing pad on the rotating surface plate and adhering it, it is necessary to align the center of the polishing pad with the rotation center of the rotating surface plate, and particularly with polishing pads for which grooves or the like have been implemented on the polishing surface, precision is needed for aligning the centers. Also, when there is an increase in the number of attachments and detachments of the polishing pad to the rotating surface plate with use of an auxiliary plate as described above, the work of aligning the centers when attaching the polishing pad to the rotating surface plate becomes even more difficult, and there is a big problem in that the labor burden becomes high.
Also, with the polishing pad with auxiliary plate proposed in JP-A-2010-214579, in order to be attachable and detachable while aligning the center of the auxiliary plate to the rotating surface plate, there are cases when an adhering means such as an outer circumference ring or the like is provided on the outer circumference surface of the rotating surface plate, for example, between the auxiliary plate and the rotating surface plate. Meanwhile, within the polishing device, a protective cover or the like is mounted on the outer circumference side of the rotating surface plate, and there are some items for which of the rotating surface plate outer circumference side space is very narrow. Therefore, if an attempt is made to use that kind of outer circumference ring using a polishing device for which the outer circumference side space of the rotating surface plate happens to be narrow, there is the risk that it will be necessary to modify the polishing device or the like.